Draft regulator



my my?! March 4, 1952 H. HOPTON ET AL DRAFT REGULATOR Filed Dec. 3, 1949 rnfvl/ENTOR.

Patented Mar. 4, 1952 =DRAFT REGULATOR Harold Hopton, Bismarck, N. Dak., and Lawrence T. Wahlstrom, Chicago, Ill.

Application December 3, 1949, Serial -No. 130,942

7-Claims.

Al This invention relates to .safety devices for .furnace draft doors .and has for its ,principal Vobject the provision of a new fand. improved device of this kind.

`Another object of the invention is to provide ,a safety device which will allow the furnace draft door to close automatically ,at a predetermined temperature and which device can be used in conjunction with existing apparatus for operating furnace draft doors.

.A further object of the invention is .to provide a safety device for furnace draft doors which can be rinstalled as an accessory to any furnace with `a minimum of effort and alteration to the furnace.

A further object ofthe invention is to provide a `furnace draft door safety device 'which 'will operate independently of either automatic 'or manual devices for manipulation of the 'draft door and 4thereby insure its safety in operation, regardless of the operating position 'of the principal 'draft door "control means.

A still further object of the invention is to provide a safety device for furnace 'draft "doors which has a minimum number of parts and Vcan 'be manufactured `at lowcost without sacrificing quality.

Further Aobj ects of the invention not specifically `mentioned here 'will be apparent from the detailed description `and claims which follow, refference `being had to the accompanying "drawings in which:

Fig. 1 is a view of a Afurnace having :the draft Adoor `safety device embodied therewith;

Fig. '2 is a plan view of the draft door `safety device `shown to a-n enlarged. scale with certain `portions cut away7 thejbetter to show 'the linvention; and

'Fig 3 is a tcp view of Athe safety 'dev-ice taken along lines 3-3 of Fig. 2 and looking fthe direction of the arrows.

In Athe prior art Aof which `we are aware, there are lmany devices 'for regulating the draft door of furnaces. Generally they are of two types: first, thermostatic devices located remotely 1of the furnace and operated to fopen and close Ithe draft door to control the `furnace fire andmaintain the area heated by the furnace at a desired temperature; and, second, devices attached `to the .furnace and controlled 'by various temperatureerespon'sive means inserted either in the fire .box orjwithin .the lfurnace acke't. These devices are not wholly satisfactory., for 'in :lnstances theypermit an unsafe condition to exist .inthe furnace, and fa freely -.drafted .fire may run ignite the soot and 'residue in the stack. In such instances, because .the fire is of such rapid exfpansion, neither the temperature .of the air with;- in the furnace jacket or of the areabeing heated bythe furnace is .increased to a degree 'high enough to activate the heat-.responsive devices and Vsuch devices vwill not act to shut the draft and retard such a fire.

In thermostatically controlled draft controls which react 'to room temperature, it 'frequently vhappens thatbecause of an open door or window the control unit keeps the draft open "and 'allows there to 'burn too brisklyfor safe operation 'and a dangerous overheating of the furnace, and va stack re may result. Similarly, an electric failure may cause such a control to keep vvthe `draft door open long enough to permit unsafe conditions to develop. In instances where drafts are controlled manually, the furnace is oftentimes forgotten and unsafe `conditions allowed to develop. It is `to providing a furnace draft door safety device that will operate effectively under the conditions mentioned that the present invention particularly relates.

The present invention provides for preventing unsafe conditions "to 'develop by inserting in the draft chain an auxiliary device that is operated by a temperature-responsive device located at 'a critical point "to lengthen the c'hain and "thereby close the draft when the *temperature at Ithat point exceeds a `safe value. A

Referring now to the drawings inmore detail. In Fig. 1, We have shown the safety device applied to conventional tvpe of hot air 'furnace l'I having "the usual draft door 2 Vconnected to "the furnace vI along its upper edge so that it tends to close. Draft door 2 is operated by chain or similar tension device 3 connected Athereto and passing upwardly over a pulley 4 to a suitable regulating Adevice 5 of either themanual or automatic type. y

VThe safety device, indicated generally at .is carried Iby chain '3 between pulley 4 and door 2 by a Ahook 1., allowing the device 6 `to travel with chain 3 as it is raised and lowered to open and close the door 2. As shown rin Figsmz and 3, the device comprises a cylindricall watchcase like housing :8 having a cylindrical projection 19 extending tangentially therefrom and `havn-1g 1a generally circular opening Hl in the .lower tion ,i'llnereoi4v A hook ,1 is connected to :the ftop `of housingp :in any suitable manner, suchas by nuts :I I.

u-A shaft .1.2, is rotatably mounted in housing y8 away and extend .itselfiinto the stack pipe 4and :sa below `the center thereof and on the aside fopf posite extension 9, with squared ends I3 of the shaft I2 extending a short distance outside the housing. A ree1 I4, mounted on shaft I2 within housing 8, carries a iiexible tension member, such as a chain I5, xed thereto and wound therearound. The free end of the chain extends through opening ,I6 and is fastened to draft door 2 in any suitable manner. Ratchet wheel I6 is mounted in juxtaposition to reel I4 so that shaft I2, reel I4 and ratchet I6 operate as a unit.

The weight of the draft door 2 pulling on chain I5 tends to rotate the reel, shaft, and ratchet counterclockwise (Fig. 2) and this rotation is prevented by the engagement of a pawl 20 with the teeth I1 of the ratchet Wheel. Pawl 20 is formed on the end of a lever I8 that is plvoted at I9 to the case 8. A spring 2|, extending between a notch 22 in the pawl, and a post 23 carried by the housing is tensioned to maintain the pawl in engagement with the teeth.

An expansible bellows 25, such as a corrugated metal bellows, for example, is mounted by suitable means such as nuts 26 in the cylindrical extension 9 of housing 8. The free end 21 of bellows 25 abuts against the free end 28 of lever IB and functions to move said lever I8 and pawl 20 out of engagement with ratchet I3, as will appear later. rIhe bellows 25 is connected in a closed system through a suitable coupling and a exlble tubing 30 to an exposure bulb 3I; and the bellows 25, tubing 3|), and bulb 3| are lled with a gaseous fluid, such as carbon tetrachloride, for example, which expands upon being heated.

Exposure bulb 3l is shown mounted in stack pipe 32 between check draft 33 and the stack 34 by Way of example only as other locations are contemplated. When the temperature in the stack pipe 32 reaches a predetermined temperature, the fluid in the system will have expanded, causing the bellows 25 to expand and shift lever I8 so as to move pawl 20, out of engagement with ratchet I6 thereby allowing reel I4 to rotate freely. The weight of door 2 and chain I5 cause the reel I 4 to rotate and unwind chain I5, thereby allowing draft door 2 to close notwithstanding that the control means 5 may still be set for an open draft door.

To reset the safety device after it has operated and allowed the draft door 2 to close, chain I5l is wound onto ree1 I4 by a key 35 which engages the portion I3 of shaft I2 which extends through housing 8. The ratchet I6 and lever I8 coact in the usual manner to allow the reel I4 to rotate until the required length of chain i5 has been wound on reel I4. If desired, a suitable stop 36 may be placed in chain I5 so as to engage the housing 8 when the desired length of chain is on the reel I4.

As long as the stack temperature remains below the predetermined temperature, the ree1 I4 remains locked against rotation and the safety device 6 and chain section I5 move as a link of control chain 3 to permit normal operation of control means 5 and chain 3 in opening and closing the draft door 2.

The safety device of the present invention is possessed of many advantages. The safety device can be used in conjunction with any chain control furnace draft door regardless of whether normal operation of the draft door is controlled by thermostatic, automatic or manual means, and will operate independently of 'such means to close the draftV door when a predetermined, dangerous temperature occurs in the stack. The tempera- -ture-responsive element of the device is located in the stack and is controlled by the temperature thereof to insure protection of the stack when other portions of the furnace system may not be heated above normal operating temperatures and would not activate control devices normally dependent thereupon.

The device of this invention can readily be installed as an accessory to existing furnaces by the simplest of operations with a minimum of furnace alteration, and the safety device as described can be manufactured at low cost Without sacrificing quality.

In the drawings and description, we have shown and described the invention as applied to a warm air furnace. As will be apparent to one skilled in the art,y the invention may equally well be used in connection with other types of heating plants such as steam, vapor, or hot water.

While we have chosen to illustrate our invention by showing and describing a preferred embodiment of it, we have done so by way of example only, as there are many modifications and adaptations which can be made by one skilled in the art, within the teachings of the invention.

Having thus complied with the statutes, and shown and described a preferred embodiment of our invention, what we consider new and desire to have protected by Letters Patent is pointed out in the appended claims.

What is claimed is:

1. As an article of manufacture, a safety device for use With a furnace having a draft door which normally tends to close, comprising: a reel, means for supporting said reel by the draft door control chain, a flexible member connected to said reel and to said door, means for winding said iiexible member onto said reel thereby to shorten the chain to permit it to open said door, means for locking said reel against counter rotation which would unwind said member, and temperature-responsive means for releasingsaid locking means thereby permitting the reel to rotate and the flexible member to unwind to close the draft door.

2. As an article of manufacture, a safety device for use with a furnace having a draft door which normally tends to close and which is operated by a flexible chain, comprising: a reel, means for supporting said reel on said chain, flexible means attached to said reel and said door, means for rotating said reel to shorten said exible means thereby enabling said chain to open said door, means for holding said ree1 against counter rotation, and a temperature-responsive means for releasing said ree1 holding means at a predetermined temperature to permit rotation of the ree1 thereby lengthening said iiexible means and allowing the draft door connected thereto to close.

3. An article of manufacture for use with a furnace having a draft door anda flexible chain control for said door, comprising: a housing adapted to be carried by said chain, a reel rotatably mounted in said housing, a section of said chain connected to said reel at one end and to said door at the other, means for turning said reel to wind said chain thereupon, a ratchet and lever means for locking said ree1 against counter rotation after winding, and a heat-responsive means for disengaging said locking means to allow rotation of said reel-to unwind saidconnected chain and lower said draft door at a predetermined temperature. 4. An article of manufacture for use with a furnace having'v a draft door and a flexible chain control for said door, comprising: a housing adapted to be carried by said chain, a reel rotatably mounted in said housing, a section of said chain connected to said reel at one end and to said door at the other, means for turning said reel to Wind said chain thereupon, a ratchet and lever means for locking said reel against counter rotation after winding; a heat-responsive means including an expansible bellows mounted in said housing to co-act with said lever, an exposure bulb connected by a flexible tube to said bellows, and a gaseous uid confined therein, said fiuid expanding said bellows as the temperature of the bulb rises to disengage said locking means and allow rotation of said reel to unwind said connected chain and lower said draft door at a predetermined temperature.

5. As an article of manufacture for use with a furnace having a draft door that normally tends to close, a draft door chain lengthening safety device, comprising: a housing, a windlass mounted in said housing, a flexible member connected to said windlass at one end and to the draft door at the other end, key means for winding said member on said windlass thereby to open said door, a ratchet and lever means to lock said windlass against unwinding rotation, heat-responsive means to unlock said locking means at a predetermined temperature to permit said member to unwind and said door to close, and a hooklike means for connecting said device in the draft door chain as a link thereof.

6. As an article of manufacture for use with a furnace having a draft door which normally tends to close and which is controlled by a chain, a chain lengthening safety device, comprising: a housing, a shaft rotatably mounted in said housing, a chain-carrying reel mounted on said shaft, a ratchet mounted on said shaft, a lever means mounted on said housing and movably engaging said ratchet to lock said shaft against unwinding rotation, spring means for maintaining said lever in engagement with said ratchet, a lever-shifting means to disengage said lever to allow rotation 6 of said shaft and reel to lengthen said control chain, said means including: an expansible bellows mounted in said housing with one end engaging said lever, a flexible tube connecting said bellows to a pressure bulb mounted in the stack of said furnace, and a gaseous fluid confined in said bellows, tubing and bulb to expand said lbellows when heated to a certain temperature and thereby shift said lever.

7. An article of manufacture for use with a furnace having the usual chain-controlled draft door, a safety device comprising: a housing, a hook means for carrying said housing by the draft control chain, a reel rotatably mounted in said housing, a flexible member attached to said reel and to said draft door, key means for Winding said member upon the reel, a ratchet mounted in said housing and connected to said reel, lever means pivotally mounted to said housing and engaging said ratchet at one end, spring means carried by said housing holding said lever in engagement with said ratchet and lock said reel against unwinding rotation, an expansible bellows means engaging the free end of said lever for shifting said lever out of engagement with said ratchet and permit rotation thereof to lengthen said draft door chain, and means to expand said bellows at a predetermined temperature, including an exposure bulb connected to said bellows by a flexible tubel and a volatile fluid sealed within said bulb, tubing and bellows.

HAROLD HOPTON. LAWRENCE T. WAHLSITROM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 700,003 Anderson May 13, 1902 777,926 Stevens Dec. 20, 1904 1,966,724 Kimball July 17, 1934 2,055,426 Celander Sept. 22, 1936 

